Which antibody is present in breast milk?

Appeared in: AIIMS Delhi NO - 2017

Explanation

Immunoglobulin A (IgA) is the primary antibody found in breast milk, particularly in colostrum, the first milk produced after birth.
It is present as secretory IgA (sIgA), a dimeric form that is highly effective at protecting mucosal surfaces.
sIgA provides passive immunity to the infant by neutralizing pathogens in the gastrointestinal and respiratory tracts, preventing them from attaching to and invading the tissues.

Option B: IgM is the first antibody produced during an initial immune response and is primarily found in the bloodstream. While present in very small amounts in breast milk, it is not the main antibody.
Option C: IgG is the most abundant antibody in the blood and provides passive immunity to the fetus by crossing the placenta, not primarily through breast milk.
Option D: IgD is found in very small amounts in the blood and on the surface of B-lymphocytes. Its primary role is to act as an antigen receptor; it is not a major secretory antibody.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Immunoglobulins and passive immunity as background academic context rather than a clinical decision trigger.
Breastfeeding is strongly recommended as the IgA provided confers crucial passive immunity, significantly reducing the risk of gastrointestinal infections (like diarrhea) and respiratory infections in newborns.
This protection is especially vital in the first few months of life when the infant's own immune system is still developing.
What if? If a mother is exposed to a pathogen (like the flu virus), her body produces specific IgA antibodies against it, which are then transferred to the infant via breast milk, providing targeted, real-time protection.

How to Approach the Question

First, identify the core of the question: it asks for the specific antibody in breast milk.
Recall the different classes of immunoglobulins and their primary locations and functions.
Associate 'secretions' (like milk, saliva, tears) with a specific antibody. This is a key characteristic of IgA.
Differentiate this from IgG, which is known for crossing the placenta, and IgM, known as the primary (first) responder in an infection.
Select the option that matches the function of providing immunity via bodily secretions.

Concept Tested & Keywords

Q_jk0Zb-Ciqw3CM9JHFluS

E6 Microbiology Essentials Sastry 4e Part 1 p. 149-151

E6 Microbiology Applied AnjuDhir 3e Part 2 p. 94-96

Practise the full AIIMS Delhi NO - 2017

Attempt every question from this paper in a timed mock, then review the full solution for each one.